Conventional blasting systems rely on a plurality of detonators to controllably fire a complement of associated charges in a desired blasting sequence. The detonators and charges are typically arranged in a plurality of boreholes along and/or around the blasting site. The detonators are interconnected by electrically conductive cables that operatively connect to a blasting machine. In most systems, the blasting machine coordinates detonation of the charges by sending a firing signal to each detonator. Typically, at each detonator the firing signal initiates a countdown from a programmed delay time. A technician programs a desired delay time into each detonator. Generally, the charges then detonate when the counters of their respective detonators decrement to zero.
More specifically, the delay time refers to the lapsed amount of time between receipt of the firing signal and actual detonation. Per conventional operating protocol, the blasting machine is individually or collectively wired to each detonator, and it transmits the firing signal upon verification of the firing lines. The firing signal initializes the counter of each detonator. In response to the firing signal, the counter decrements an amount equal to the downloaded delay time, until detonation of the respective charges.
One or more of such detonators conventionally reside within each borehole of a site designated for blasting. A predetermined pattern of boreholes is typically drilled for a blasting area, according to site conditions and desired performance specifications. These specifications may include rock density, powder factor, fragmentation, excavation, bench height, crushing and vibration considerations, among others. Generally, the detonators have no initial delay time preprogrammed into their memory when placed into the boreholes by technicians.
When programming the delay times using conventional methods, one or more field technicians must find the locations of the boreholes by referring to a map or other plan, and then program the detonators contained therein. Usually, the technicians find and identify the boreholes by sight and/or by stepping off a distance in the field. This practice requires skill, organization and awareness, as a blasting site may include hundreds of largely indiscernible boreholes. Consequently, it is easy for even a seasoned team of technicians to become temporarily disoriented in the field, often requiring them to backtrack and/or to re-do their work. Additionally, the difficulties associated with this conventional practice can frustrate a team of technicians in a blasting operation, and this can create a dangerous situation.
This task may be further complicated in situations when the technicians must calculate the delay times while in the field; based on the locations of the boreholes. Despite the criticality of such calculations and the expertise of most technicians, these field calculations are susceptible to error. Other critical responsibilities of the technicians include logging all of these respective delay times and assuring that proper blasting information has been downloaded to each detonator.
One prior art blasting system, disclosed in U.S. Pat. No. 6,079,333, issued to Manning uses data derived from a GPS (Global Positioning System) to establish a blast program. More particularly, a master controller uses a GPS-based time when detonating an explosive.
Similarly, European Patent Application 0897098 discloses a blasting system that uses GPS position data to calculate delay times for the detonators. This is done at one location, by a central controller. Neither of these prior systems specifically addresses the practical problems faced by technicians in the field that relate to finding and accurately programming a plurality of detonators at a blast site.
It is an object of this invention to reduce or eliminate the errors and/or imprecisions currently associated with conventional methods of programming a plurality of detonators used in a blasting operation.
It is another object of this invention to simplify and facilitate the programming of delay times in a plurality of detonators used in a blasting operation.
It is still another object of this invention to facilitate the logging and tracking of blasting data used for a plurality of detonators at a blasting site.
It is still another object of this invention to make it faster and easier for technicians in the field to find a plurality of boreholes used in a blasting operation.